I've run bags with 5ers and TT's. When using them with TT's the best way IMO is to load your truck up with the stuff you put in the bed, air up the bags to reset the truck rear to it's OEM ride height.
Then hitch up and use the WDH to set the front.
Never hitch up then air up. If you're using a friction based WDH you'll be relieving too much friction when airing up. Whats happening is you're lifting the rear up which takes less weight off the spring bars.
If you're not hauling a heavy load in the bed then bags are unnecessary.
Here's a video explaining how bags vs WDH works.
I currently have bags on my 2500 from towing a previous 5er. I run about 10 lbs in them when towing the TT.